Seafloor geomagnetic observatory program in France

摘要: The accurate determination of the main geomagnetic field and its secular variation at global scale remains limited by number observatories their poor distribution over Earth's surface, particularly ocean areas. This biases significantly source geometry even very long wavelength. In France, a collaborative action is undertaken to build semi-permanent seafloor observatory that matches INTERMAGNET measurement requirements. comprises triaxial variometer an Overhauser magnetometer measuring absolute total intensity. difficulty declination, which needs known geographical reference within few tens arc-seconds. declination may be obtained using precise mechanical gyro. A full working has been built tested. going deployed in North Pacific Ocean site H2O September 2003 along with US for intercomparison qualification measurement.